Serialize Objects to Client

I am creating a game that would have the server and client send information about objects periodically. Mostly at level loads and character creation. I was thinking about serializing the objects and then using a commandtoserver/commandtoclient scheme to exchange this information.

Is this going to be slow when I have say 100 objects of the complexity of a player object (datablock and object)?

Is there a better way to do this?

I want to retain multiplayer capability by design even though it will not be a main feature of the game. The game will primarily be a one person game. Is there a way to transfer files instead?